Holstein cow feeding grass

Feeding yeast improves performance of dairy cows under heat stress

Alvaro Garcia

Hot summer temperatures are a highly limiting factor for milk production of dairy cows. To maintain body temperature, cows reduce intake, which decreases the heat increment that results from rumen fermentation. In order to improve milk production under these conditions it is necessary to restore intake, and/or improve nutrient digestibility. Since forage fiber requires more time for its degradation in the rumen, it produces more heat of fermentation than concentrates.

Less fiber in the diet however, results in less chewing, reduced saliva production, more grain fermentation, and ultimately a more acidic rumen pH. These changes shift the pattern of fermentation from predominantly acetate to propionate→lactate, risking the appearance of sub-clinical or clinical rumen acidosis. Past research has demonstrated that feeding live yeasts or yeast cultures increases milk production of cows under heat stress.

Could Saccharomyces cerevisiae help cows under heat stress?

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A glass and a milk jug

Effects of yeast supplementation in transition cows

Fernando Diaz

During the last 3 weeks of gestation, cow’s requirements for energy increase due to fetal development and colostrum production. At the same time, dry matter (DM) intake drops significantly during this period. This mismatch between nutrient intake and demand generates a negative energy balance towards the end of the pregnancy that is prolonged for several weeks after calving. Additionally, health problems during the transition period have a negative impact on the profitability of the operation due to increased veterinary expenses, reduced production, reduced reproduction performance, early culls, and deaths.

Despite increased research studying the transition period, these problems continue to manifest themselves and have even increased over the years. This increase is likely associated with the parallel genetic improvement and resulting milk production increase per cow. Recently, a study published in Animal Feed Science and Technology evaluated how a yeast supplement would affect milk production, blood metabolites, and body reserves of transition dairy cows during hot weather.

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